Palestinian sources say the number of casualties from the latest round of Israeli airstrikes in Gaza has risen to 10 dead and at least 20 wounded.

Israeli warplanes carried out air raids over the Gaza Strip on Wednesday and Thursday after Palestinian militants fired rockets into southern Israel.

More rockets struck southern Israel on Thursday.

Palestinian sources said at least one militant from the Islamic Jihad group was among those killed in the airstrikes.

Escalating retaliation

Israeli forces and Palestinian militants have traded attacks across the Gaza border for the past week, since militants crossed into southern Israel and attacked a bus, cars and security personnel on August 18. Eight Israelis were killed.

Pursuing the attackers, Israeli troops killed some of the assailants along Israel's border with Egypt's Sinai peninsula. Five Egyptian officers were also killed, sparking outrage and anti-Israel protests in Egypt.

Israeli Prime Minister Benjamin Netanyahu offered Thursday to hold a joint investigation with Egypt into the killing of the Egyptian officers. A statement issued by Netanyahu's national security adviser said military officials on both sides would set terms of the probe.

Egypt's military-backed government threatened to withdraw its ambassador to Israel to protest the killings. Egypt blamed the deaths on Israeli troops it said had violated the 1979 Israel-Egypt peace treaty.

Some information for this report was provided by AP and Reuters.

Follow our Middle East reports on Twitter and discuss them on our Facebook page.